1. Field of the Invention
The present invention relates to a camera having a light emitting function which emits auxiliary light for image capture, a method to control the emission of auxiliary light for image capture, and a storing medium which stores a program to control emission of auxiliary light for image capture.
2. Description of the Related Art
A conventional image capture apparatus, such as a digital camera or a mobile phone having a camera function, is equipped with an image sensor such as a CCD. Image capture with the conventional image capture apparatus is performed as follows. Before starting exposure, an electronic shutter pulse (charge sweep-out pulse) is continuously supplied to the image sensor so as to sweep out charges accumulated in the image sensor. At the start of exposure, the sweep of the accumulated charges stops. An amount of the charges which is proportional to an amount of incident light is accumulated. Therefore, image data is acquired. Exposure is stopped in such a manner that a mechanical shutter is closed to block the incident light, or the charge sweep is resumed by an electronic shutter function.
The digital camera generally captures an image of an object with automatic emission of a flash when, for example, capturing the image at night. In the flash photography, the flash is automatically emitted according to a flash emission control pulse, immediately after the stop of the electronic shutter pulse. The pulse width of the flash emission control pulse is varied in order to control an emission period within an exposure time. Therefore, the amount of light is adjusted (see Jpn. Pat. Appln. KOKAI Publication No. 2004-32681).
However, when performing the above light amount adjustment, the brightness of the ordinary flash changes with the emission period. The flash light remains unstable at the rising thereof. Namely, the flash light is unstable before the brightness reaches to a half of a waveform peak. When the digital camera is equipped with a flash lamp having a color temperature of about 5,500 K at full emission, the color temperature within the rise time is about 8,000 K and the flash light becomes bluish. Consequently, a shorter emission period causes more bluish flash light and degrades color reproducibility of the captured image.